Galvanic cell



P. A. MARSAL GALVANI 0 CELL 1 Nov. 17, 193 6,

Filed Nov. l0, 1932 I NVENTOR PAUL A; NARGAL.

ATTORND Patented Nov. 17, 1936- v UNITED-STATES PATENT OFFICE.

GALVANIC CELL Paul A. Marsal, Lakewood, Ohio, asaignor, by mesne assignments, to-Union Carbide and Carbon Corporation, a corporation of New York Application November 10, 1e32, Serial No. 642,068 18 claims; (01'. 136-133) This invention relates to galvanic cells, and These and other objects and the novel features more specifically to dry cells in'which the sealing will appear in the following description and the closure comprises a metal or metals electroaccompanying illustration showing a sectional chemically different from one of the electrodes, view taken longitudinally through the center of 5 particularly the anode, and in which at least a a dry cell embodying one example of an appli- 5 part of the surface of such closure is exposed cation of this invention. within the cell. In such cells, the sealing closure According to this invention, electrolytic conmay comprise an annular metal, disc having its tamination of the metal closure surfaces exouter margin secured to the upper end of the posed within the cell is prevented or inhibited by outer electrode or anode and having its inner. a barrier or apron which is secured to the upper 10 margin disposed adjacent the metal cap on the end of the outer or metal electrode, to the outer upper end of the inner electrode, and a dielectric margin of the cell closure, or to both, and which forming a mechanical continuity and an electric extends downwardly and inwardly toward the gap between said disc and said cap. inner or carbon electrode. This barrier pro- 5 Very serious eificiency losses occur in such vides a much longer creepage path between the 5 cells when the exposed interior metal surfaces closure and the body of electrolyte, as well as a of the closure become moistened with a film of trough in a position to hold a substantial quanelectrolyte communicating with the main body tity of electrolyte, thus preventing migration and of electrolyte. For example, suchmoistening of .access of the electrolyte to the closure.

the internally exposed portion of the usual brass The drawing shows the invention applied to a 20 cap onthe central carbon electrode establishes modern dry cell which comprises an outer zinc a bleeding circuit which may exhaust the cell in container electrode or anode H]; a central inner a short time; and in less severe cases may cause carbon electrode H; a cylindrical depolarizer copper to be dissolved in the cell, which greatly mix or bobbin it in whichthe lower end of the increases the rate of local action at the anode electrode ii is embedded; a gelatinized elec- 25 and shortens the shelf life of the cell. When a trolyte I3 inan annular space between the anode similar electrolytic contamination is established l0 and the bobbin l2; a brass cap [4 mounted at the joint between the usual zinc anode and on the upper end of the electrode H; a dielecthe sealing disc of different or more electrotric washer I5 of pulpboard or the like carried positive metal, such as iron, therate of local by an outturned flange it at the lower edge of 30 action at the anode increases and the shelf life .the cap M; and a resilient annular sheet iron of the cell is reduced. disc l1 having its outer margin permanently se- It is common practice to place a highly bibulous cured to the upper end of the anode l0 and havseparator in contact with the anode of a dry ing its inner margin yieldingly engaging the cell, which separator consists of, or is coated washer 15. The height of the bobbin l2 and the 35 with, a pasty electrolyte. The electrolytic connormal level of the electrolyte l3 are such as to itamination or moistening of the top'structure in, leave a gas space It in the cell below the sealing the cell is due chiefly to the expansion and mi-' closure provided by the disc H, the cap 14, and gration of this electrolyte within the cell. The the washer l5 clamped 'therebetween. 40 expansion and migration may result either'from The protective barrier or baflie of this inven- 40 especially heavy use of the cell or even idle stortion consists of an annular dished or substanage under severe conditions of temperature and tially frusto-conical apron 20 which is preferhumidity. Contamination also results in those ably secured in the joint between the anode l0 cells in which the electrolyte is of sufiicient fiuidand the sealing disc i1, andextends downwardity to flow to the top when the cell is inverted or ly and inwardly into the space I8 and is dis- 45 rests on its side for a period of time. posed at an angle to both the anodeand the disc. Therefore, the principal objects of the inven- The inner margin of the apron 20 may be turned tion are: to inhibit or prevent electrolytic con-. downward more or less than shown and its intamination of the exposed metal surfaces of the her edge is preferably spaced from the electrode top structure of a dry cell; and to provide a ll to avoid electrical contact with the latter 5 simple and inexpensive means for this purpose when the apron is made of metal and to leave which may be readily embodied in the wella'free passage through which cell gas may reach known type of dry cell without reducing the cathe vent or vents in the closure. In the absence pacity of the cell or detracting from its utility of a protective barrier and when the disc I1 or appearance. 1 consists of iron, electrolyte reaching the joint 55 between disc I! and the zinc anode III will establish an electromotive couple tending to increase local action at the anode. The apron 20 is preferably formed of material which is identical with the anode [0, since contact with the electrolyte then can set up no detrimental electromotive couples and a. substantial increase in active anode area. is also provided. However, the apron may consist of other materials, such as fiber or pulpboard, which will not form part of a couple. When the construction at the cathode exposes connection members such as brass or copper inside the sealing disc, fiber, zinc or even iron aprons are useful.

- Various methods may be employed to properly secure the apron in place and unite the sealing disc and the anode. As shown, the upper end '22 of\the anode I is ofiset inwardly and then flares outwardly. The outer margin .23 of the apron is shaped to 1% flat against and rests upon the inner inclined face of the outwardly flaring end 22, the edges of the parts 22 and 23 being substantially coextensive. The assembly is completed by tightly clamping the parts 22 and 23, so disposed, within and between the walls of an annular recess 24 in the outer margin 25 of the sealing disc I1, thereby forming a fluid-tight joint of compression which permanently unites the disc, anode, and apron, and

prevents the passage of gas and liquid through this joint.

The space between the under side of apron 20 turned to an upright position, whereupon it will drain back to its original position around the cathode mix l2.

The electrolyte will creep over the surface of a metal, suchas the zinc electrode, more readily .than over the surface of a non-metal, such as the carbon electrode. The long creepage path provided by the apron therefor substantially prevents migration of electrolyte to the closure and thus avoids the creation of galvanic couples between the closure and the anode. Where the apron and anode are of the same metal, such as zinc, any film of electrolyte that may form on the underside of the apron increases the active anode area and improves the efllciency oi the cell.

The protective-barrier may be of other forms and located in other positions and secured by different means than those here shown. It will be understood thatother changes may be made in the details herein disclosed without departing from the principles of the invention.

I claim:

1. In a galvanic cell comprising a metal container anode, a closure comprising metal different from that of said container, and an electrolyte that tends to creep over the inner surfaces of said metals and form deleterious galvanic couples therebetween; means for increasing the length of the creepage path betweensaid electrolyte and said closure comprising a barrier extending from said container into said cell between said electrolyte and said closure.

2. A galvanic cell according to claim 1, in which said barrier consists of metal.

3. A galvanic cell according to claim 1, in which said anode and said barrier are both of metal and have substantially identical electrochemical properties.

4. A galvanic cell according to claim 1, in which said barrier consists of fiber or the like.

5. A galvanic cell according to claim 1, in which said barrier is secured to said anode.

6. A galvanic cell according to claim 1, in which said closure is secured to said anode and said barrier is disposed between the inner surfaces of said anode and said closure.

7. A galvanic cell according to claim 1, in which said barrier cooperates with said anode to provide a trough.

8. A galvanic cell according to claim 1, in which a gas collecting space is provided between said closure and said electrolyte, and said barrier is secured to said anode and extends into said gas space.

9. A galvanic cell according to claim 1, in which said anode, said closure, and said barrier are united by a fluid-tight joint of compression.

A galvanic cell according to claim 1, in which said closure is secured to the upper end of said container, a gas space is provided below said closure, and said barrier is secured to said container and extends inwardly and downwardly therefrom into said space.

11. A galvanic cell according to claim 1, in which said anode is a cylindrical container, and said barrier is a substantially frusto-conical apron having its outer margin secured to said container and extending inwardly and downwardly within said container.

12. A galvanic cell according to claim 1, in which said anode'is a cylindrical container, said cell comprises an electrode disposed centrally in .said container, a gas space isprovided in'said tainer electrode, a cooperating electrode therein,-

a body of electrolyte between said electrodes, a sealing closure for said cell comprising a metal electrochemically diilerent from that of said container, and a metal apron secured to the inner side of said container electrode and-extending inwardly above said body of electrolyte below said closure, electrochemical properties of the metals of said container and said apron being substantially identical.

14. A dry cell according to claim 13, in which said container and said apron both consist of zinc, said cell has a gas space between said closure and said body of electrolyte, and said apron projects into said space and is normally spaced from said body of electrolyte and from said cooperating electrode.

v 15. A dry cell comprising a container electrode; an electrode disposed centrally in said container electrode; an electrolyte between said electrodes; a sealing closure for the cell permanently secured to said container electrode and comprising metal exposed within the cell; a gas space below said closure; and a barrier to inhibit electrolytic contamination of such exposed metal, comprising a substantially Irusto-conical apron permanently secured between said closure and saidcontainer by a fluid-tight joint and extending inwardly" and downwardly Irom said Joint into said gas space and having its inner margin spaced from such central electrode.

16. A dry cell comprising a metal container electrode, a cooperating electrode therein, a body of electrolyte between said electrodeaa sealing closure for said cell comprising metal exposed within the cell and electrochemically difierent from said container electrode, and means in the cell permanently and fluid-tightly secured to said container electrode between said body of electrolyte and said exposed metal for substantially increasing the length of the creepage path between said body of electrolyte and such exposed metal and inhibiting electrolytic contamination of the latter.

1'7. A dry cell comprising a cylindrical zinc container electrode;'a cathode therein having a central carbon electrode, a body of electrolyte between said cathode and said zinc'electrode; a sealing closure-for said cell comprising a brasscap on said carbon electrode, an annular resilient Y iron disc having its outer margin permanently joined to the upper end of said zinc container and its inner margin supported by said cap, por

tions of said cap and said disc being exposed within said cell; a gas collecting space in the cell between said closure and said body of electrolyte; and means in the cell substantially increasing the length of the creepage path between said body of electroiyte and such exposed metal portions and substantially preventing electrolytic contamination of the latter, said means comprising a substantially frusto-conical zinc apron having its outermargin secured to the joint between said container and disc and extending downwardly and inwardly therefrom into said gas space but spaced from said carbon electrode.

18. A dry cell comprising a cylindrical metallic container electrode; a centrally disposed carbon cathode therein; a body of electrolyte between said cathode and said container; a sealing clo-- sure for said cell comprising a metal cap on said carbon electrode, an annular metallic disc having its outer-margin permanently joined to the upper end of said container and its inner margin adjacent to.and electrically insulated from said cap, portions of said cap and said disc being exposed within said cell; a gas collecting space in the cell between said closure and said body of electrolyte; and means in the cell substantially increasing the length of the creepage path between said body of electrolyte and such exposed metal portions and. substantially preventing electrolytic contamination, of the latter, said means comprising a barrier extending from said container into said cell between said electrolyte and said closure.- v

PAUL A. MARSAL. 

